Surface Electromyography as a Method for Characterizing Mammogram Discomfort: Cross-Sectional Questionnaire Study of Procedural Stress

TL;DR

This study uses surface electromyography to objectively measure muscle activity and stress during mammograms, revealing which muscles are most affected and how discomfort is experienced.

Contribution

The study introduces a novel sEMG-based method to objectively quantify mammogram-related stress and muscle activity.

Findings

The deltoid showed the highest muscle activation during mammogram simulations, with up to 436% increase in activity.

Muscle activations were ipsilaterally correlated, with significant differences when the breast was compressed on the same side as the measured muscle.

Patient-reported discomfort primarily localized to the shoulder and neck, aligning with the physiological data.

Abstract

Mammograms are the most readily used procedures for early breast cancer detection but are notorious for the discomfort they induce in patients. This physiological strain has been validated by many questionnaire-based investigations, some of which indicate that it may discourage and deter women from potentially lifesaving health care. While informative, these subjective measures are highly variable and do not provide an objective perspective regarding the coordinated physiological and ergonomic response required for the procedure.

A multimuscle surface electromyography (sEMG) methodology is proposed to better understand the machine-patient dynamics and potentially develop objective measures of mammogram-related pain and stress.

Seven different muscle pairs on the neck, shoulders, and torso were identified as being critical in postural positioning during the industry-standard mammogram procedure. sEMG was recorded during 8 compressions across 2 mammogram simulations for 25 women wearing wireless devices. An illustrative map of muscle activity was created based on a comprehensive 10-metric sEMG analysis that compared baseline recordings with activated states during each compression.

The deltoid demonstrated the highest muscular activation across trials with an increase in the mean of the root mean square activity of up to 436%, while the trapezius upper fibers, infraspinatus, and teres major also showed significant increases in muscle activation, averaging 89% to 155% when compared with rest states. Across metrics, muscle activations were ipsilaterally correlated, with significant differences observed only when the breast was compressed on the same side as the muscle being measured. The serratus anterior and external oblique muscles showed minimal activation for any compression or positioning. No significant differences were found between curved and flat paddle designs. After the breast, patient-reported discomfort localized primarily to the shoulder and neck regions, corroborating the physiological measurements.

The juxtaposition of muscle-specific activity against inactive muscles, along with reported discomfort values, demonstrates that the sEMG methodology accurately captures the patient-machine interaction dynamics with objective, quantifiable precision that complements subjective feedback. By providing real-time physiological data on muscular patterns and biomechanical responses throughout the procedure, this sEMG-based approach offers measurable metrics for evaluating proposed improvements to mammogram equipment design and protocols.

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